40,891 research outputs found
Preparation to the CMB PLANCK data analysis, estimation of the contamination due to the galactic polarized emissions
This work is point of the preparation to the analysis of the PLANCK satellite
data. The PLANCK satellite is an ESA mission which has been launched the 14th
of may 2009 and is dedicaced to the measurement of the Cosmic Microwave
Background (CMB) in temperature and polarization. The presence of diffuse
Galactic polarized emissions disturb the measurement of the CMB anisotropies,
in particular in polarization. Therefore a precise knowledge of these emissions
is needed to obtain the level of accuracy required for PLANCK. In this context,
we have developed and implemented a coherent 3D model of the two mains
polarized Galactic emissions : synchrotron and thermal dust. We have compared
these models to preexisting data: the 23 GHz band of the WMAP data, the 353 GHz
Archeops data and the 408 MHz all-sky continuum survey. We extrapolate these
models to the frequencies where the CMB dominates and we are able to estimate
the contribution of polarized foreground emissions to the polarized CMB
emission measured with PLANCK.Comment: Proceeding of the International Workshop on Cosmic Structure and
Evolution - Cosmology2009, September 23-25, 2009 Bielefeld, German
Weight-area trade-off study for a flat SNAP-8 radiator
Weight-area tradeoff evaluation of radiator used in SNAP-
SNAP-8 third loop optimization
Eutectic sodium potassium and OS-124 considered as coolant fluids for SNAP-8 third loop - optimum loop operating parameter
Fast on-wafer electrical, mechanical, and electromechanical characterization of piezoresistive cantilever force sensors
Validation of a technological process requires an intensive characterization of the performance of the resulting devices, circuits, or systems. The technology for the fabrication of micro and nanoelectromechanical systems (MEMS and NEMS) is evolving rapidly, with new kind of device concepts for applications like sensing or harvesting are being proposed and demonstrated. However, the characterization tools and methods for these new devices are still not fully developed. Here, we present an on-wafer, highly precise, and rapid characterization method to measure the mechanical, electrical, and electromechanical properties of piezoresistive cantilevers. The setup is based on a combination of probe-card and atomic force microscopy technology, it allows accessing many devices across a wafer and it can be applied to a broad range of MEMS and NEMS. Using this setup we have characterized the performance of multiple submicron thick piezoresistive cantilever force sensors. For the best design we have obtained a force sensitivity ℜ_F = 158μV/nN, a noise of 5.8 μV (1 Hz–1 kHz) and a minimum detectable force of 37 pN with a relative standard deviation of σ_r ≈ 8%. This small value of σr, together with a high fabrication yield >95%, validates our fabrication technology. These devices are intended to be used as bio-molecular detectors for the measurement of intermolecular forces between ligand and receptor molecule pairs
Floquet interface states in illuminated three-dimensional topological insulators
Recent experiments showed that the surface of a three dimensional topological
insulator develops gaps in the Floquet-Bloch band spectrum when illuminated
with a circularly polarized laser. These Floquet-Bloch bands are characterized
by non-trivial Chern numbers which only depend on the helicity of the
polarization of the radiation field. Here we propose a setup consisting of a
pair of counter-rotating lasers, and show that one-dimensional chiral states
emerge at the interface between the two lasers. These interface states turn out
to be spin-polarized and may trigger interesting applications in the field of
optoelectronics and spintronics.Comment: 5 pages with 3 figures + supplemental materia
Source energy spectra from demodulation of solar particle data by interplanetary and coronal transport
The data on source energy spectra of solar cosmic rays (SCR), i.e. the data on the spectrum form and on the absolute SCR are of interest for three reasons: (1) the SCR contain the energy comparable to the total energy of electromagnetic flare radiation (less than or equal to 10 to the 32nd power ergs); (2) the source spectrum form indicates a possible acceleration mechanism (or mechanism); and (3) the accelerated particles are efficiently involved in nuclear electromagnetic and plasma processes in the solar atmosphere. Therefore, the data on SCR source spectra are necessary for a theoretical description of the processes mentioned and for the formulation of the consistent flare model. Below it is attempted to sound solar particle sources by means of SCR energy spectrum obtained near the Sun, at the level of the roots of the interplanetary field lines in the upper solar corona. Data from approx. 60 solar proton events (SPE) between 1956-1981. These data were obtained mainly by the interplanetary demodulation of observed fluxes near the Earth. Further, a model of coronal azimuthal transport is used to demodulate those spectra, and to obtain the source energy spectra
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